Miles Lane wrote:
On Tue, Jun 10, 2008 at 7:15 PM, Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote:
Miles Lane wrote:
I got a slightly different BUG with this patch applied:
BUG: unable to handle kernel NULL pointer dereference at 00000000
IP: [<f89e3d41>] :b43:b43_dma_mapping_error+0x16/0x97
*pde = 00000000
Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
last sysfs file:
/sys/devices/pci0000:00/0000:00:08.0/0000:01:06.0/ssb0:0/firmware/ssb0:0/loading
Modules linked in: sbs sbshc wmi battery iptable_filter ip_tables
x_tables ac sbp2 rtc arc4 ecb crypto_blkcipher cryptomgr crypto_algapi
b43 mac80211 cfg80211 led_class snd_intel8x0 snd_ac97_codec ac97_bus
snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss
snd_seq_midi_event snd_seq snd_timer snd_seq_device snd soundcore
snd_page_alloc i2c_nforce2 i2c_core button ohci1394 3c59x ieee1394
forcedeth ehci_hcd ohci_hcd usbcore thermal processor fan thermal_sys
Miles,
If you have time, please cd to the kernel root directory and run the command
'objdump -d -l drivers/net/wireless/b43/dma.o > dmadump'. You may have to
install the objdump package. In the file dmadump, find the line that
contains b43_dma_mapping_error. On my system it is 0000000000000085
<b43_dma_mapping_error>: Note, I use x86_64 and yours will likely be
different.
Note the address (0x85 in my case), add the offset (0x16) and find the line
with the error. You can use KCalc in hexadecimal mode if you are not
comfortable with doing addition in base 16. Please report the source line
and instruction that failed.
For me, the line is:
"000000ab <b43_dma_mapping_error>:"
so, 0xab + 0x16 = 0xc1
and here's the dump giving some context around that line:
b43_dma_mapping_error():
ab: 55 push %ebp
ac: 89 e5 mov %esp,%ebp
ae: 57 push %edi
af: 89 d7 mov %edx,%edi
b1: 56 push %esi
b2: 89 ce mov %ecx,%esi
b4: 53 push %ebx
b5: 83 ec 08 sub $0x8,%esp
b8: 8a 55 08 mov 0x8(%ebp),%dl
bb: 88 55 ef mov %dl,-0x11(%ebp)
be: 8b 50 58 mov 0x58(%eax),%edx
c1: 8b 12 mov (%edx),%edx
c3: 8b 52 08 mov 0x8(%edx),%edx
c6: 89 55 f0 mov %edx,-0x10(%ebp)
c9: 8b 40 34 mov 0x34(%eax),%eax
cc: 83 f8 1e cmp $0x1e,%eax
cf: 74 07 je d8 <b43_dma_mapping_error+0x2d>
d1: 83 f8 20 cmp $0x20,%eax
d4: 75 5b jne 131 <b43_dma_mapping_error+0x86>
d6: eb 15 jmp ed <b43_dma_mapping_error+0x42>
The line that fails is
if (unlikely(dma_mapping_error(ring->dev->dev->dma_dev, addr)))
The value at 0x58(%eax) is zero, which corresponds to the "struct
b43_wldev *dev" line in struct b43_dmaring. In other words, ring->dev
is NULL, which causes the error. I'll leave it to FUJITA Tomonori to
figure out why.
Larry
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